U.S. patent number 9,445,425 [Application Number 14/353,907] was granted by the patent office on 2016-09-13 for method of transmission in a communications network.
This patent grant is currently assigned to Nokia Solutions and Networks Oy. The grantee listed for this patent is Thomas Chapman, Frank Frederiksen, Jani Matti Johannes Moilanen, Jeroen Wigard. Invention is credited to Thomas Chapman, Frank Frederiksen, Jani Matti Johannes Moilanen, Jeroen Wigard.
United States Patent |
9,445,425 |
Chapman , et al. |
September 13, 2016 |
Method of transmission in a communications network
Abstract
A method of transmission in a communications network is provided
in which data is transmitted using a first radio access technology
and a second radio access technology. The method includes providing
an anchor carrier associated only with the first radio access
technology and another carrier shared between the first radio
access technology and the second radio access technology.
Transmission via the second radio access technology is muted in the
shared carrier during at least one subframe of each data frame
transmitted using the second radio access technology. Data is
transmitted using the first radio access technology in the shared
carrier only during the at least one subframe in which transmission
using the second radio access technology is muted.
Inventors: |
Chapman; Thomas (Stockholm,
SE), Frederiksen; Frank (Klarup, DK),
Moilanen; Jani Matti Johannes (Helsinki, FI), Wigard;
Jeroen (Klarup, DK) |
Applicant: |
Name |
City |
State |
Country |
Type |
Chapman; Thomas
Frederiksen; Frank
Moilanen; Jani Matti Johannes
Wigard; Jeroen |
Stockholm
Klarup
Helsinki
Klarup |
N/A
N/A
N/A
N/A |
SE
DK
FI
DK |
|
|
Assignee: |
Nokia Solutions and Networks Oy
(Espoo, FI)
|
Family
ID: |
44860371 |
Appl.
No.: |
14/353,907 |
Filed: |
October 24, 2011 |
PCT
Filed: |
October 24, 2011 |
PCT No.: |
PCT/EP2011/068528 |
371(c)(1),(2),(4) Date: |
April 24, 2014 |
PCT
Pub. No.: |
WO2013/060350 |
PCT
Pub. Date: |
May 02, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140293974 A1 |
Oct 2, 2014 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
72/1215 (20130101); H04W 72/0453 (20130101); H04W
16/14 (20130101) |
Current International
Class: |
H04W
72/12 (20090101); H04W 16/14 (20090101); H04W
72/04 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO2004057893 |
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Jul 2004 |
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WO |
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WO2008081309 |
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Jul 2008 |
|
WO |
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WO2008088253 |
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Jul 2008 |
|
WO |
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WO2010091713 |
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Aug 2010 |
|
WO |
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Other References
Working Group C; White Paper Multi-RAT Network Architecture (Nov.
2013). cited by examiner.
|
Primary Examiner: Mills; Donald
Assistant Examiner: Baron; Henry
Attorney, Agent or Firm: Harrington & Smith
Claims
The invention claimed is:
1. A method comprising: providing an anchor carrier associated only
with a first radio access technology for providing continuous
transmission via the first radio access technology and another
carrier shared between the first radio access technology and a
second radio access technology; muting transmission via the second
radio access technology in the shared carrier during at least one
subframe of each data frame transmitted using the second radio
access technology; and transmitting data using the first radio
access technology based on code division multiplexing in the shared
carrier only during the at least one subframe in which transmission
using the second radio access technology is muted, wherein data
transmitted using the code division multiplexed transmission to a
user associated with the first radio technology is split into a
first part having an additional time-multiplex structure and a
second part having continuous transmission such that the first part
contains only packet user data channels and packet user data
associated signalling channels and is transmitted on the shared
carrier and the second part contains all dedicated channels
associated with the packet user data channels, radio access related
channels, broadcast and synchronization channels and is transmitted
only on the anchor carrier.
2. The method according to claim 1, wherein data frames are
transmitted from a first cell of a communications network using the
first radio access technology and from a second cell of the
communications network using the second radio access
technology.
3. The method according to claim 2, wherein the second cell is
adjacent to the first cell.
4. The method according to claim 2, wherein the second cell at
least partially overlaps the first cell.
5. The method according to claim 2, further comprising
synchronizing transmission of data frames transmitted via the first
radio technology with transmission of data frames transmitted via
the second radio access technology such that a start time of
transmission of a subframe of a data frame transmitted via the
first radio access technology is the same as a start time of
transmission of every other subframe of a data frame transmitted
via the second radio access technology.
6. The method according to claim 1, wherein a first subframe of a
data frame transmitted via the first radio access technology is
synchronized with a first subframe of a data frame transmitted via
the second radio access technology and transmission via the first
radio access technology takes place during a second subframe of the
data frame transmitted via the first radio access technology.
7. The method according to claim 1, wherein a first subframe of a
data frame transmitted via the first radio access technology is
synchronized with a second subframe of a data frame transmitted via
the second radio access technology and transmission via the first
radio access technology takes place during the first subframe of
the data frame transmitted via the first radio access
technology.
8. The method according to claim 1, wherein a pilot signal is
transmitted using the first radio access technology in the anchor
carrier.
9. An apparatus for a communications network, comprising a
processor; and a non-transitory memory including computer program
code, the memory and the computer program code are configured to,
with the processor, cause the apparatus to: provide an anchor
carrier associated only with a first radio access technology and
another carrier shared between the first radio access technology
and a second radio access technology, wherein the anchor carrier is
configured to provide continuous transmission via the first radio
access technology; mute transmission via the second radio
technology in the shared carrier during at least one subframe of
each data frame transmitted using the second radio access
technology; and transmit data using the first radio access
technology based on code division multiplexing in the shared
carrier only during the at least one subframe in which transmission
using the second radio access technology is muted, and wherein data
transmitted using the code division multiplexed transmission to a
user associated with the first radio technology is split into a
first part having an additional time-multiplex structure and a
second part having continuous transmission such that the first part
contains only packet user data channels and packet user data
associated signalling channels and is transmitted on the shared
carrier and the second part contains all dedicated channels
associated with the packet user data channels, radio access related
channels, broadcast and synchronization channels and is transmitted
only on the anchor carrier.
10. A computer program product comprising a non-transitory computer
readable medium having a program comprising software portions
embodied thereon, the software portion executable by a processor,
to cause a device to perform at least: providing an anchor carrier
associated only with a first radio access technology for providing
continuous transmission via the first radio access technology and
another carrier shared between the first radio access technology
and a second radio access technology; muting transmission via the
second radio access technology in the shared carrier during at
least one subframe of each data frame transmitted using the second
radio access technology; and transmitting data using the first
radio access technology based on code division multiplexing in the
shared carrier only during the at least one subframe in which
transmission using the second radio access technology is muted,
wherein the data transmitted using code division multiplexed
transmission to a user associated with the first radio technology
is split into a first part having an additional time-multiplex
structure and a second part having continuous transmission such
that the first part contains only packet user data channels and
packet user data associated signalling channels and is transmitted
on the shared carrier and the second part contains all dedicated
channels associated with the packet user data channels, radio
access related channels, broadcast and synchronization channels and
is transmitted only on the anchor carrier.
11. The method according to claim 1, wherein the first radio access
technology is High Speed Packet Access.
12. The method according to claim 1, wherein the second radio
access technology is Long Term Evolution or Long Term Evolution
Advanced.
13. The apparatus according to claim 9, wherein the processor is
further arranged to cause the apparatus to: transmit data frames
from a first cell of a communications network using the first radio
access technology and from a second cell of the communications
network using the second radio access technology.
14. The apparatus according to claim 13, wherein the processor is
further arranged to cause the apparatus to: synchronize
transmission of data frames transmitted via the first radio
technology with transmission of data frames transmitted via the
second radio access technology such that a start time of
transmission of a subframe of a data frame transmitted via the
first radio access technology is the same as a start time of
transmission of every other subframe of a data frame transmitted
via the second radio access technology.
15. The apparatus according to claim 9, wherein the processor is
further arranged to cause the apparatus to: synchronize a first
subframe of a data frame transmitted via the first radio access
technology with a first subframe of a data frame transmitted via
the second radio access technology and transmission via the first
radio access technology takes place during a second subframe of the
data frame transmitted via the first radio access technology.
16. The apparatus according to claim 9, wherein the processor is
further arranged to cause the apparatus to: synchronize a first
subframe of a data frame transmitted via the first radio access
technology with a second subframe of a data frame transmitted via
the second radio access technology and transmission via the first
radio access technology takes place during the first subframe of
the data frame transmitted via the first radio access
technology.
17. The apparatus according to claim 9, wherein the processor is
further arranged to cause the apparatus to: transmit a pilot signal
using the first radio access technology in the anchor carrier.
18. The apparatus according to claim 9, wherein the first radio
access technology is High Speed Packet Access.
19. The apparatus according to claim 9, wherein the apparatus
comprises a base station.
Description
FIELD OF THE INVENTION
The invention generally relates to a method of transmission in a
communications network. More particularly, the invention relates to
transmission in a communications network that supports two radio
access technologies such as High Speed Packet Access (HSPA) and
Long Term Evolution (LTE).
BACKGROUND OF THE INVENTION
Current radio technologies such as LTE and LTE-Advanced (LTE-A)
have been developed with maximum flexibility in mind in terms of
deployment within the same radio technology. LTE and LTE-A are
radio access technologies that provide a number of options for
bandwidth utilization ranging from 1.4 MHz to 20 MHz per carrier
(or per cell in 3GPP terminology) and duplexing distances (there
are no tight dependencies on the duplex distance apart from being
within a 100 kHz channel raster). In addition, both systems support
both TDD and FDD modes of operation.
Furthermore, LTE and LTE-Advanced systems support deployment with
frequency reuse 1, meaning that all neighbouring cells can use the
same carrier frequency.
However, LTE and LTE-A have not been designed for ensuring a
"natural migration path" for the physical layer. This means that
network operators with limited spectrum resources currently used
for existing radio technologies such as HSPA would need to either
acquire new spectrum resources to introduce a new radio technology,
or perform a "hard switch" between radio technologies. This would
provide a number of current/legacy UEs with a significantly worse
user experience, since part of the spectrum would be assigned to
LTE, or even render them completely useless if the entire legacy
spectrum were assigned to LTE.
Most modern communications networks are designed with very little
or even no provision for ensuring a smooth transition path from
previous/legacy systems to the new radio access technology.
The invention has been devised with the foregoing in mind.
SUMMARY OF THE INVENTION
Accordingly, the invention provides a method of transmission in a
communications network in which data is transmitted using a first
radio access technology based on code division multiplexing and
requiring continuous transmission and a second radio access
technology. The method includes providing an anchor carrier
associated only with the first radio access technology for
providing continuous transmission via the first radio access
technology and another carrier shared between the first radio
access technology and the second radio access technology, muting
transmission via the second radio access technology in the shared
carrier during at least one subframe of each data frame transmitted
using the second radio access technology, and transmitting data
using the first radio access technology in the shared carrier only
during the at least one subframe in which transmission using the
second radio access technology is muted. Data transmitted using
code division multiplexed transmission to a user associated with
the first radio technology is split into a first part having an
additional time-multiplex structure and a second part having
continuous transmission such that the first part contains only
packet user data channels and packet user data associated
signalling channels and is transmitted on the shared carrier (and
on the anchor carrier) and the second part contains all dedicated
channels associated with the packet user data channels, radio
access related channels, broadcast and synchronization channels and
is transmitted only on the anchor carrier.
In a communications network in which data is transmitted using a
first radio access technology based on code division multiplexing
and requiring continuous transmission and a second radio access
technology, an anchor carrier is provided, which is associated only
with the first radio access technology The anchor carrier provides
continuous transmission via the first radio access technology.
Another carrier is provided, which is shared between the first
radio access technology and the second radio access technology.
Transmission via the second radio access technology is muted in the
shared carrier during at least one subframe of each data frame
transmitted using the second radio access technology. Then data is
transmitted using the first radio access technology in the shared
carrier only during the time in which the second radio access
technology is muted. Data transmitted using code division
multiplexed transmission to a user associated with the first radio
technology is split into a first part having an additional
time-multiplex structure and a second part having continuous
transmission such that the first part contains only packet user
data channels and packet user data associated signalling channels
and is transmitted on the shared carrier (and on the anchor
carrier) and the second part contains channels that are required to
be transmitted continuously.
Allowing transmission via the first radio access technology in the
shared carrier when transmission via the second radio access
technology is muted allows the spectrum to be shared in any desired
proportion. In this way an available spectrum in a communications
network may be shared between two different systems, namely the two
radio access technologies, in a flexible and dynamic way. Although
the code division multiplexed-based first radio access technology
requires continuous transmission, the data transmitted using this
technology may be split into two parts--one with a time division
multiplex structure and one with continuous transmission so that
channels requiring continuous transmission are only transmitted on
the anchor carrier, whereas other channels can be transmitted on
the shared carrier (and on the anchor carrier as well if required).
This allows two different systems to be combined and means that a
communications network may benefit from the features of both
systems.
The first radio access technology may be HSPA, for example, and the
second radio access technology may be LTE or LTE-A.
The number of shared carriers provided can be dependent on a number
of user equipment capable of using the second radio access
technology. For example, if there are only a small number of user
equipment or mobile stations in the network that are able to use
the second radio access technology, only one shared carrier may be
needed but as the number of UEs able to use the second radio access
technology increases more shared carriers can be provided. For
example, in a network having a frequency spectrum of 20 MHz
(4.times.5 MHz frequency bands or carriers) one 5 MHz band can be
the anchor carrier (used only by the first radio access technology)
and between one and three 5 MHz bands can be used as shared
carriers capable of being used by both the first and second radio
access technologies. This provides increased flexibility as to how
the network capacity is shared between the two radio access
technologies.
In one embodiment, data frames are transmitted from a first cell of
the communications network using the first radio access technology
and from a second cell of the communications network using the
second radio access technology. The second cell may be adjacent to
the first cell and/or may at least partially overlap the first
cell.
In this case, transmission of data frames transmitted via the first
radio technology may be synchronized with transmission of data
frames transmitted via the second radio access technology such that
a start time of transmission of a subframe of a data frame
transmitted via the first radio access technology is the same as a
start time of transmission of every other subframe of a data frame
transmitted via the second radio access technology.
A first subframe of a data frame transmitted via the first radio
access technology may be synchronized to an nth subframe of a data
frame transmitted via the second radio access technology.
In one embodiment, a first subframe of a data frame transmitted via
the first radio access technology is synchronized with a first
subframe of a data frame transmitted via the second radio access
technology and transmission via the first radio access technology
takes place during a second subframe of the data frame transmitted
via the first radio access technology.
In another embodiment, a first subframe of a data frame transmitted
via the first radio access technology is synchronized with a second
subframe of a data frame transmitted via the second radio access
technology and transmission via the first radio access technology
takes place during the first subframe of the data frame transmitted
via the first radio access technology.
A pilot signal may be transmitted using the first radio access
technology in the anchor carrier.
The invention further provides an apparatus for a communications
network. The apparatus includes a first transmitter configured to
transmit data using a first radio access technology based on code
division multiplexing and requiring continuous transmission in an
anchor carrier associated only with the first radio access
technology and in another carrier shared between the first radio
access technology and a second radio access technology. The anchor
carrier is configured to provide continuous transmission via the
first radio access technology. A second transmitter is configured
to transmit data using the second radio access technology in the
shared carrier and a processing unit is configured to mute
transmission from the second transmitter during at least one
subframe of each data frame transmitted using the second radio
access technology. The first transmitter is configured to transmit
data using the first radio access technology in the shared carrier
only during the at least one subframe in which transmission using
the second radio access technology is muted. The first transmitter
is further configured to transmit data using code division
multiplexed transmission to a user associated with the first radio
technology, whereby the data is split into a first part having an
additional time-multiplex structure and a second part having
continuous transmission. The first part of the data contains only
packet user data channels and packet user data associated
signalling channels and is transmitted on the shared carrier (and
on the anchor carrier). The second part of the data contains all
dedicated channels associated with the packet user data channels,
radio access related channels, broadcast and synchronization
channels and is transmitted only on the anchor carrier.
Preferably, the apparatus is a base station. The base station may
be a Node B configured for HSPA operation, an eNode B configured
for LTE or LTE-A operation, or an eNode B configured for HSPA, LTE
and LTE-A operation. Some control functionality may take place in a
radio network controller (RNC) controlling the base station,
although scheduling may be performed in the base station.
The invention also provides a computer program product including a
program comprising software portions being arranged, when run on a
processor, to perform a method of transmission in a communications
network in which data is transmitted using a first radio access
technology based on code division multiplexing and requiring
continuous transmission and a second radio access technology. The
method includes providing an anchor carrier associated only with
the first radio access technology for providing continuous
transmission via the first radio access technology and another
carrier shared between the first radio access technology and the
second radio access technology, muting transmission via the second
radio access technology in the shared carrier during at least one
subframe of each data frame transmitted using the second radio
access technology, and transmitting data using the first radio
access technology in the shared carrier only during the at least
one subframe in which transmission using the second radio access
technology is muted. Data transmitted using code division
multiplexed transmission to a user associated with the first radio
technology is split into a first part having an additional
time-multiplex structure and a second part having continuous
transmission. The first part contains only packet user data
channels and packet user data associated signalling channels and is
transmitted on the shared carrier (and on the anchor carrier is
required) and the second part contains all dedicated channels
associated with the packet user data channels, radio access related
channels, broadcast and synchronization channels and is transmitted
only on the anchor carrier.
Preferably, the computer program product includes a computer
readable medium on which the software code portions are stored,
and/or wherein the program is directly loadable into a memory of
the processor.
The invention will now be described, by way of example only, with
reference to specific embodiments and to the accompanying drawings,
in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified schematic diagram of a wireless
communications network;
FIG. 2 is a simplified schematic diagram of a network apparatus
according to an embodiment of the invention;
FIG. 3 is a simplified schematic diagram illustrating sharing of an
available frequency spectrum in a communications network between
different radio access technologies;
FIG. 4 is a simplified schematic diagram illustrating sharing of an
available frequency spectrum in a communications network between
different radio access technologies;
FIG. 5 is a simplified schematic diagram illustrating time division
multiplexed transmission patterns of two different radio access
technologies in a shared carrier in a communications network;
FIG. 6 is a simplified schematic diagram of a wireless
communications network; and
FIG. 7 is a flow chart illustrating a method according to an
embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
FIG. 1 shows a wireless communications network according to one
embodiment of the invention. Mobile stations or user equipment
(UEs) 1 and 2 may access the network over a radio interface with a
base station BS1, which is located in the cell C1.
The base station BS1 is an enhanced Node B (e-Node B), which is
capable of transmission and reception of data with the UEs 1 and 2
via both HSPA and LTE-A radio access technologies. To this end, the
base station BS1 is provided with two transceiver units TR1 and
TR2, as shown in FIG. 2, as well as a processor P. The transceiver
TR1 is configured for the HSPA radio access technology and the
transceiver TR2 is configured for the LTE-A radio access
technology.
If the operator of the communications network wishes to implement a
dynamic migration path from HSPA to LTE-A, the LTE part of the
frequency spectrum is configured with muting patterns such that
some fraction of radio spectrum can be used as a secondary spectrum
for HSPA connected UEs. This means that the network operator
provides an HSPA-only anchor carrier deployed beside the LTE-A
carrier.
This is shown in more detail in FIGS. 3 and 4, where the network
operator has a total of 20 MHz (4.times.5 MHz carriers) of
frequency spectrum for use of 3GPP radio access technologies. One
of the four carriers is a so-called anchor carrier. This anchor
carrier is associated only with HSPA and does not carry any LTE
channels. The anchor carrier is capable of providing continuous
transmission via HSPA. The other three 5 MHz carriers are shared
carriers, which may be used for both HSPA and LTE-A.
Since HSPA is based on code division multiplexing, it requires
continuous transmission. If the UEs UE1 and UE2 are associated with
HSPA, data transmitted to the UEs UE1 and UE2 using code division
multiplexed transmission in HSPA can be split into two parts by the
base station BS1. The first part of the data has an additional
time-multiplex structure and contains only packet user data
channels and packet user data associated signalling channels. This
part of the data can be transmitted on the shared carriers, as well
as on the anchor carrier. The second part of the data is
transmitted continuously only on the anchor channel and contains
all dedicated channels associated with the packet user data
channels, radio access related channels, broadcast and
synchronization channels.
If, for example, the operator has a large penetration of HSPA
capable UEs and would like to start deploying LTE-A in a "soft
way", rather than reserving a fixed set of resources for the LTE-A
radio access technology, the operator has 4 HSPA carriers, which
are operated using the quad-cell configuration in HSPA. As the
operator starts bringing the LTE-A radio access technology into
operation, one of the carriers will become shared between HSPA and
LTE-A radio technologies, as shown in FIG. 3, with the option to
carry both HSPA and LTE-A traffic between the LTE-A capable UEs and
the network.
If the penetration of LTE-A capable UEs increases in the network
(or in the case where the operator would like to offer higher peak
data rates to the LTE-A UEs), the frequency spectrum configuration
shown in FIG. 4 can be used.
Here, the fraction of the spectrum shared between HSPA and LTE-A is
significantly increased (to 15 MHz) so that there are three shared
5 MHz carriers deployed beside the HSPA-only anchor carrier, and
the network will be capable of carrying larger amounts of LTE-A
data traffic.
Within the carrier(s) shared between the HSPA and LTE-A radio
access technologies, data traffic is time multiplexed and
transmission in LTE-A is muted during subframes (timeslots in HSPA)
of a data frame transmitted from the base station BS1. Data is then
only transmitted using HSPA in the shared carrier during the
subframes in which LTE-A transmission is muted. (In HSPA a
transmission time interval (TTI) is 1 ms, which is twice the length
of an LTE-A subframe of 2 ms).
The exact approach used for this dynamic spectrum sharing between
the two radio access technologies is illustrated in FIG. 5. LTE-A
transmission occurs in the first and fifth subframes of every
transmitted LTE data frame and is muted during other subframes.
HSPA transmission may occur in only some or all of the subframes in
which LTE-A transmission is muted, depending on whether or not the
start of an HSPA dataframe coincides with the start of an LTE-A
dataframe.
The UEs 1 and 2 are configured to perform radio related
measurements at certain time instants to ensure that handover
measurements and CSI measurements are happening according to
desired time instants. In this embodiment, it is assumed that base
station BS1 acts as a Node B (base station for HSPA) as well as an
e-Node B (base station for LTE-A) so that HSPA and LTE-A
transmission are already synchronized in time and the muting and
transmission patterns used are coordinated between HSPA and LTE-A
by algorithms run on the processor P of the base station BS1.
It is shown in FIG. 5 that two HSPA transmission patterns or
configurations are possible during the time in which LTE-A
transmission is muted.
The times during which HSPA transmission may take place in the
shared carrier during muting of LTE-A transmission depends on when
the TTI starts in HSPA. If the TTI starts at the first subframe
(subframe 0) of an LTE-A dataframe, the first TTI (2 ms) of HSPA
cannot be used for HSPA transmission, since the first subframe (1
ms) of LTE-A is used for transmission of LTE common channels.
However, the next HSPA TTI may be used for HSPA transmission but
the TTI after that cannot, since it coincides with LTE-A
transmission in LTE subframe 5. If, however, the HSPA TTI starts at
subframe 1 of an LTE-A data frame, HSPA transmission may take place
in the first HSPA TTI, as well as in the second HSPA TTI.
The shared carrier will have to transmit LTE-A common channels to
ensure that mobility and basic synchronization in LTE is
maintained. This means that LTE common channels such as the PSS/SSS
(primary and secondary synchronization channels), PBCH (physical
broadcast channel) and SI (system information) needs to be
transmitted when they occur. Therefore, it is not possible to use
every subframe of a data frame for HSPA transmission.
However, it can be seen from FIG. 5 that in principle it is
possible to carry up to 60% HSPA traffic in an LTE-configured cell.
In other words, up to 60% of the LTE capacity in the time domain
can be given to the HSPA users in the cell and provide a dynamic
balancing of load between the two radio access technologies.
The benefits of the dynamic spectrum sharing provided by the
invention include a faster and more flexible adaptation to load,
since shared carriers can be active all the time for both radio
access technologies. Therefore the UEs 1 and 2 may also stay
connected to the shared carrier during a spectrum shift.
Another embodiment of the invention is illustrated in FIG. 6. In
this embodiment, the UEs 1 and 2 are at the border of two cells C2
and C3 of a wireless communications network, accessible via base
stations BS2 and BS3, respectively. The cells C2 and C3 are
adjacent and may overlap each other. The UEs 1 and 2 may exchange
data with both base stations BS2 and BS3 using HSPA and/or LTE-A.
In this illustrative example, the base station BS2 transmits using
HSPA and the base station BS3 transmits using LTE.
The method of transmission according to this embodiment is exactly
the same as in the previous embodiment described above and is
illustrated in the flow chart in FIG. 7. In step S1 an anchor
carrier is provided, which is one 5 MHz band of the 20 MHz spectrum
available to the network and is associated only with HSPA
transmission, as well as one or more shared carriers shared between
HSPA and LTE-A. In step S2, LTE-A transmission is muted in the
shared carrier(s) (in this embodiment transmission from the base
station BS3 is muted) during one or more subframes of an LTE-A
dataframe. Then in step S3 data is transmitted using HSPA in the
shared carrier (in this embodiment from the base station BS2) only
during the subframe(s) in which LTE-A transmission in muted.
However, in this example the two network nodes (base stations BS2
and BS3) used for transmission of HSPA and LTE-A are not co-located
and mechanisms for ensuring time-synchronization and coordination
of the LTE-A muting patterns shown in FIG. 5 are required.
Therefore an additional step S1a takes place after step S1 in this
embodiment, whereby transmission to the UEs 1 and 2 of data frames
via HSPA from the base station BS2 is synchronized with
transmission of data frames via LTE-A from the base station BS1.
The start time of transmission of an LTE-A subframe should be the
same as the start time of every other HSPA TTI, since an HSPA TTI
is 2 ms, whereas an LTE subframe is 1 ms. Any known synchronization
mechanism already defined for coordination between e-Node Bs in
LTE-A may be used for this purpose.
For the purpose of the present invention as described hereinabove,
it should be noted that method steps likely to be implemented as
software code portions and being run using a processor at a network
control element or terminal (as examples of devices, apparatuses
and/or modules thereof, or as examples of entities including
apparatuses and/or modules therefore), are software code
independent and can be specified using any known or future
developed programming language as long as the functionality defined
by the method steps is preserved; generally, any method step is
suitable to be implemented as software or by hardware without
changing the idea of the embodiments and its modification in terms
of the functionality implemented; method steps and/or devices,
units or means likely to be implemented as hardware components at
the above-defined apparatuses, or any module(s) thereof, (e.g.,
devices carrying out the functions of the apparatuses according to
the embodiments as described above) are hardware independent and
can be implemented using any known or future developed hardware
technology or any hybrids of these, such as MOS (Metal Oxide
Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS),
BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL
(Transistor-Transistor Logic), etc., using for example ASIC
(Application Specific IC (Integrated Circuit)) components, FPGA
(Field-programmable Gate Arrays) components, CPLD (Complex
Programmable Logic Device) components or DSP (Digital Signal
Processor) components; devices, units or means (e.g. the
above-defined apparatuses and network devices, or any one of their
respective units/means) can be implemented as individual devices,
units or means, but this does not exclude that they are implemented
in a distributed fashion throughout the system, as long as the
functionality of the device, unit or means is preserved; an
apparatus may be represented by a semiconductor chip, a chipset, or
a (hardware) module comprising such chip or chipset; this, however,
does not exclude the possibility that a functionality of an
apparatus or module, instead of being hardware implemented, be
implemented as software in a (software) module such as a computer
program or a computer program product comprising executable
software code portions for execution/being run on a processor; a
device may be regarded as an apparatus or as an assembly of more
than one apparatus, whether functionally in cooperation with each
other or functionally independently of each other but in a same
device housing, for example.
In general, it is to be noted that respective functional blocks or
elements according to above-described aspects can be implemented by
any known means, either in hardware and/or software, respectively,
if it is only adapted to perform the described functions of the
respective parts. The mentioned method steps can be realized in
individual functional blocks or by individual devices, or one or
more of the method steps can be realized in a single functional
block or by a single device.
Generally, any method step is suitable to be implemented as
software or by hardware without changing the idea of the present
invention. Devices and means can be implemented as individual
devices, but this does not exclude that they are implemented in a
distributed fashion throughout the system, as long as the
functionality of the device is preserved. Such and similar
principles are to be considered as known to a skilled person.
The terms "user equipment (UE)" and "mobile station" described
herein may refer to any mobile or stationary device including a
mobile telephone, a computer, a mobile broadband adapter, a USB
stick for enabling a device to access to a mobile network, etc.
The exemplary embodiments of the invention have been described
above with reference to a communications network supporting HSPA
and LTE-A. However, the above-described examples may be applied to
any wireless communications network.
Although the invention has been described hereinabove with
reference to specific embodiments, it is not limited to these
embodiments and no doubt further alternatives will occur to the
skilled person that lie within the scope of the invention as
claimed.
For example the invention does not have to apply to HSPA and LTE-A
technologies. The first radio access technology does not have to be
code division multiplexed and continuously transmitted so that the
invention may also be applied to WiMAX and LTE technologies, for
example.
LIST OF ABBREVIATIONS
3GPP 3rd generation partnership project
eICIC Enhanced inter-cell interference coordination
LTE Long term evolution
LTE-Advanced Long term evolution-Advanced
MIB Master Information block
CSG Closed subscriber group
PBCH Physical broadcast channel
TDM Time-domain mux
UE User equipment
eNB evolved Node B (base station for LTE)
eICIC Enhanced inter-cell interference coordination
SI System information
PSS Primary Synchronization channel
SSS Secondary Synchronization channel
DSR Dynamic Spectrum Refarming
* * * * *